| 1. |
- Alizadehgiashi, Moien, et al.
(författare)
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Multifunctional 3D-Printed Wound Dressings
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:7, s. 12375-12387
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Tidskriftsartikel (refereegranskat)abstract
- Personalized wound dressings provide enhanced healing for different wound types; however multicomponent wound dressings with discretely controllable delivery of different biologically active agents are yet to be developed. Here we report 3D-printed multicomponent biocomposite hydrogel wound dressings that have been selectively loaded with small molecules, metal nanoparticles, and proteins for independently controlled release at the wound site. Hydrogel wound dressings carrying antibacterial silver nanoparticles and vascular endothelial growth factor with predetermined release profiles were utilized to study the physiological response of the wound in a mouse model. Compared to controls, the application of dressings resulted in improvement in granulation tissue formation and differential levels of vascular density, dependent on the release profile of the growth factor. Our study demonstrates the versatility of the 3D-printed hydrogel dressings that can yield varied physiological responses in vivo and can further be adapted for personalized treatment of various wound types.
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| 2. |
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| 3. |
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| 4. |
- Brett, Calvin, et al.
(författare)
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Water-Induced Structural Rearrangements on the Nanoscale in Ultrathin Nanocellulose Films
- 2019
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 52:12, s. 4721-4728
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Tidskriftsartikel (refereegranskat)abstract
- Many nanoscale biopolymer building blocks with defect-free molecular structure and exceptional mechanical properties have the potential to surpass the performance of existing fossil-based materials with respect to barrier properties, load-bearing substrates for advanced functionalities, as well as light-weight construction. Comprehension and control of performance variations of macroscopic biopolymer materials caused by humidity-driven structural changes at the nanoscale are imperative and challenging. A long-lasting challenge is the interaction with water molecules causing reversible changes in the intrinsic molecular structures that adversely affects the macroscale performance. Using in situ advanced X-ray and neutron scattering techniques, we reveal the structural rearrangements at the nanoscale in ultrathin nanocellulose films with humidity variations. These reversible rearrangements are then correlated with wettability that can be tuned. The results and methodology have general implications not only on the performance of cellulose-based materials but also for hierarchical materials fabricated with other organic and inorganic moisture-sensitive building blocks.
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| 5. |
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| 6. |
- Brouzet, Christophe, et al.
(författare)
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Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers on the Nanoscale
- 2019
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 52:6, s. 2286-2295
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Tidskriftsartikel (refereegranskat)abstract
- Polydisperse fiber networks are the basis of many natural and manufactured structures, ranging from high-performance biobased materials to components of living cells and tissues. The formation and behavior of such networks are given by fiber properties such as length and stiffness as well as the number density and fiber-fiber interactions. Studies of fiber network behavior, such as connectivity or rigidity thresholds, typically assume monodisperse fiber lengths and isotropic fiber orientation distributions, specifically for nano scale fibers, where the methods providing time-resolved measurements are limited. Using birefringence measurements in a microfluidic flow-focusing channel combined with a flow stop procedure, we here propose a methodology allowing investigations of length-dependent rotational dynamics of nanoscale polydisperse fiber suspensions, including the effects of initial nonisotropic orientation distributions. Transition from rotational mobility to rigidity at entanglement thresholds is specifically addressed for a number of nanocellulose suspensions, which are used as model nanofiber systems. The results show that the proposed method allows the characterization of the subtle interplay between Brownian diffusion and nanoparticle alignment on network dynamics.
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| 7. |
- Brouzet, Christophe, et al.
(författare)
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Effect of Electric Field on the Hydrodynamic Assembly of Polydisperse and Entangled Fibrillar Suspensions
- 2021
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 37:27, s. 8339-8347
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Tidskriftsartikel (refereegranskat)abstract
- Dynamics of colloidal particles can be controlled by the application of electric fields at micrometer-nanometer length scales. Here, an electric field-coupled microfluidic flow-focusing device is designed for investigating the effect of an externally applied alternating current (AC) electric field on the hydrodynamic assembly of cellulose nanofibrils (CNFs). We first discuss how the nanofibrils align parallel to the direction of the applied field without flow. Then, we apply an electric field during hydrodynamic assembly in the microfluidic channel and observe the effects on the mechanical properties of the assembled nanostructures. We further discuss the nanoscale orientational dynamics of the polydisperse and entangled fibrillar suspension of CNFs in the channel. It is shown that electric fields induced with the electrodes locally increase the degree of orientation. However, hydrodynamic alignment is demonstrated to be much more efficient than the electric field for aligning CNFs. The results are useful for understanding the development of the nanostructure when designing high-performance materials with microfluidics in the presence of external stimuli.
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| 8. |
- Brouzet, Christophe, et al.
(författare)
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Size-Dependent Orientational Dynamics of Brownian Nanorods
- 2018
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Ingår i: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 7:8, s. 1022-1027
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Tidskriftsartikel (refereegranskat)abstract
- Successful assembly of suspended nanoscale rod-like particles depends on fundamental phenomena controlling rotational and translational diffusion. Despite the significant developments in fluidic fabrication of nanostructured materials, the ability to quantify the dynamics in processing systems remains challenging. Here we demonstrate an experimental method for characterization of the orientation dynamics of nanorod suspensions in assembly flows using orientation relaxation. This relaxation, measured by birefringence and obtained after rapidly stopping the flow, is deconvoluted with an inverse Laplace transform to extract a length distribution of aligned nanorods. The methodology is illustrated using nanocelluloses as model systems, where the coupling of rotational diffusion coefficients to particle size distributions as well as flow-induced orientation mechanisms are elucidated.
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| 9. |
- Cohen, Céline, et al.
(författare)
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Parallelised production of fine and calibrated emulsions by coupling flow-focusing technique and partial wetting phenomenon
- 2014
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Ingår i: Microfluidics and Nanofluidics. - : Springer. - 1613-4982 .- 1613-4990. ; 17:5, s. 959-966
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of microfluidic technology to fabricate monodisperse emulsion droplets is well established. Parallelisation of droplet production is a prerequisite for using such an approach for making high-quality materials for either fundamental or industrial applications where product quantity matters. Here, we investigate the emulsification efficiency of parallelised drop generators based on a flow-focusing geometry when incorporating the role of partial wetting in order to make emulsion droplets with a diameter below 10 μm. Confinement intrinsically encountered in microsystems intensifies the role played by interfaces between liquids and solids. We thus take advantage of partial wetting to enhance the maximum confinement accessible due to liquid flow focusing. We compare the performances brought by partial wetting to more established routes such as step emulsification. We show that the step configuration and the partial wetting regime are both well suited for being parallelised and thus open the way to the production of fine and calibrated emulsions for further applications. Finally, this new route of emulsification that exploits partial wetting between the fluids and the channel walls opens possibilities to the formation of substantially smaller droplets, as required in many fields of application.
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| 10. |
- Geng, Lihong, et al.
(författare)
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Understanding the Mechanistic Behavior of Highly Charged Cellulose Nanofibers in Aqueous Systems
- 2018
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 51:4, s. 1498-1506
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Tidskriftsartikel (refereegranskat)abstract
- Mechanistic behavior and flow properties of cellulose nanofibers (CNFs) in aqueous systems can be described by the crowding factor and the concept of contact points, which are functions of the aspect ratio and concentration of CNF in the suspension. In this study, CNFs with a range of aspect ratio and surface charge density (380-1360 mu mol/g) were used to demonstrate this methodology. It was shown that the critical networking point of the CNF suspension, determined by rheological measurements, was consistent with the gel crowding factor, which was 16. Correlated to the crowding factor, both viscosity and modulus of the systems were found to decrease by increasing the charge density of CNF, which also affected the flocculation behavior. Interestingly, an anomalous rheological behavior was observed near the overlap concentration (0.05 wt %) of CNF, at which the crowding factor was below the gel crowding factor, and the storage modulus (G') decreased dramatically at a given frequency threshold. This behavior is discussed in relation to the breakup of the entangled flocs and network in the suspension. The analysis of the mechanistic behavior of CNF aqueous suspensions by the crowding factor provides useful insight for fabricating high-performance nanocellulose-based materials.
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